Which is the encryption key in threshold FHE?

Library Questions
1

Hi,

In the threshold-fhe.cpp example, the encryption key used is for the second part. Is it the case that the last party is the one whose public key is used for encryption?

And would’nt make the last party be able to decrypt the ciphertext since it has the private key equivalent for that public key?

Thanks in advance

2

Basically in threshold FHE, all parties participate in generating a common encryption key. But their private keys cannot be used to decrypt. Each party needs to do a partial decryption with their private key, and then all the resulting partials are combined to form a final plaintext decryption. Hope that helps.